Comparing Polymer Bearings with Traditional Bearings
The term "polymer bearing" is a broad category, encompassing a wide array of materials, each with a unique set of properties and ideal applications. The strength of polymer bearings as a technology lies in this diversity. Engineers can select a specific polymer, and often a custom-compounded version of that polymer, to precisely match the performance requirements of a given application. From high-strength components to ultra-low friction surfaces, there is a polymer for almost every job.
One of the most widely used materials is Nylon (Polyamide). Nylon is a strong and tough material with excellent wear resistance, making it a popular choice for general-purpose bearings. It can withstand moderate loads and has good a low coefficient of friction. However, Nylon has one significant drawback: it is hygroscopic, meaning it absorbs moisture from the air. This moisture absorption can cause the material to swell and change dimensions, which is a major concern for parts that require tight tolerances. This makes it a less ideal choice for precision applications in humid environments.
Another common and versatile material is POM (Polyoxymethylene or Acetal). Often referred to as a "workhorse" polymer, Acetal has a great combination of strength, stiffness, and low friction. Unlike Nylon, it has excellent dimensional stability and does not readily absorb moisture, making it a reliable choice for precision components. Acetal is widely used in a variety of applications, from automotive components to consumer electronics, and is a great all-around choice for many bearing needs.
For applications where friction is the number one concern, engineers turn to PTFE (Polytetrafluoroethylene or Teflon). Known for being one of the slipperiest substances in existence, PTFE has an incredibly low coefficient of friction. However, in its pure form, PTFE is very soft and has poor wear resistance, which limits its ability to handle high loads. To overcome this, PTFE is often compounded with fillers such as glass fibers, carbon, or bronze to improve its strength and wear properties while maintaining its low friction.
Finally, for the most demanding applications, there is PEEK (Polyetheretherketone). PEEK is considered a high-performance polymer due to its exceptional properties. It has a high continuous service temperature, excellent chemical resistance, and is incredibly strong and durable. While it is significantly more expensive than other polymers, its ability to perform in extreme environments—such as in aerospace, medical, and oil and gas applications—justifies the cost. By choosing the right material from this diverse family, engineers can create a bearing that is not only self-lubricating but also perfectly tailored to the specific demands of the application, ensuring optimal performance and a long service life.
